πŸ‡¬πŸ‡§ Sinclair ZX Spectrum: Part 3 (Refurbishing continues) [TCE #0448]

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Australia The Clueless Engineer
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Published on ● Video Link: https://www.youtube.com/watch?v=6rK55bcnGPQ


Duration: 29:54
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Work continues on refurbishing this Issue 2 Speccy in a Fuller FDS case. Unfortunately it seems I've encountered an issue with the Speccy now so more troubleshooting is required.

Ivan, a subscriber, very kindly donated one of his 128KByte RAM expansion boards so I am looking forward to trying that out - my first package from πŸ‡·πŸ‡Έ Serbia! In order for it to work you need to disable the upper 32KBytes of internal RAM, which I've done by adding a switch to inhibit the !CAS signal for that bank of RAM (make one OR gate input on IC23 always HIGH by connecting to +5V thus forcing the output HIGH, thus disabling !CAS).

I've verified the switch works by executing "PRINT PEEK 23732 + 256 * PEEK 23733" : I get 65535 (full 48KBytes), or 32767 (upper 32KBytes disabled).

However, after this it seems things started to go awry (nothing to do with Ivan's board).

I've added in various right-angled plugs for MIC/EAR and power, and replaced the original [RESET] button. I've also strengthened the keyboard cables.

I now have a vLA82 and a vLA1 - the vLA82 replaces the original ULA and also adds RGBS output (Harlequin or Spectrum +2 pinout apparently).

The vLA1 replaces the ULA in the ZX Interface 1 (not worried about that at the moment).

Link to Ivan's Github:
https://github.com/goloskokovic/zx16to128upgrade

That time I went to πŸ‡¦πŸ‡± Albania (day trip via ferry from Corfu):
https://youtu.be/u_O6kuYrmFI

Replacement ULAs:
https://www.vretrodesign.com



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